I just had the same problem and figured it out. Here’s the solution for posterity:
On the transcript page, there is no option to share/create a link for the transcript, if you haven’t completed any courses on Microsoft’s site learn.microsoft.com.
I found a course, “Describing cloud services” and completed it in about 5 minutes. Then my transcript was created and a link to share it appeared. Badabing badaboom, I got the transcript ID.
@mods, the steps should be updated to include the detail that your transcript doesn’t exist until you complete a Microsoft lesson first.